fur & xgen Point position render element have an offset to other objects

[mschreck]

I noticed that my xgen hair and vray fur have an offset in the world position pass.This is clearly visible when connecting it to the nuke "PositionToPoints" node.
The point positions value on the xgen hair is offset by around 10 in the green channel and by 2 in the red channel.

Every other geometry on my character using basic vray materials doesn´t show this problem.

any ideas what could be causing this?

maya 2022.2
V-Ray 5 for Maya, update 2
(v5.20.00 from Nov 9 2021)
Windows 10

[Dimitrina.Milanova]

Hello,

Is it possible to send us a scene and video/screenshots of the problem you are facing?

Kind Regards,
Dimitrina

[mschreck]

Hi Dimitrina,
unfortunately I can´t and I´m not able to reproduce the problem with a test sphere so far.
I´m continuing to investigate on how to reproduce that behaviour and will send something that is not covered by NDA

[mschreck]

okay, I managed to reproduce the problem on a clean sphere using my vray fur coming from my maya reference.The problem doesn´t show up if i create new fur inside that scene.
Attached is a screenshot on how the green position pass channel looks like in nuke when i tone down the fstops.As you can see the values of the referenced fur is much much higher than the sphere even though they are very close to each other
I´m investigating further if referencing is actually the problem

[mschreck]

I could boil it down to my hair shader settings. When using a standard preset all is good. But i dont know yet which value is responsible.
Here´s a side by side of default hair shaders world position and my customized hair shader.

I´m also attaching a scene with this

[mschreck]

I just testetd, the Transparency slider on the VRayHairNextMtl changes the world position in the render lement. If set to 1 or 0 all is good. when something inbetween i get the offsetted values.
Furthermore its only in the world position generated by the VrayDenoiser Element. I though this would be the same as the sampler info Point

[Dimitrina.Milanova]

Hello again,

I have logged an issue into our system, for our developers to have further look into the problem.
This is the issue ID Tracker Number (VMAYA-10928 )
Thank you for reporting!

Kind Regards,
Dimitrina